PJ is exactly right.
I am amazed by the extent to which non-investors seem mystified by capital gains tax issues.
Since the tax is levied on realizations, not accumulated gains, investors can easily make choices that reduce their tax liability. When the rate is low (as it is now) the incentive to do so is limited. But if you were to increase the cap gains tax rate to, say, 35% (the current top rate on ordinary income) taxable realizations would dry up so fast it would make your head swim. For one thing, it would create an incentive to delay realization until the taxable gain could be partially or totally mitigated by offsetting losses in the same tax year. In the case of stocks and other financial assets, it's usually very easy to "protect" unrealized gains by means of options or other hedging strategies.
Another way investors can dodge the bullets is by simply borrowing against appreciated assets instead of selling them.
Scroll down and take a look at the chart posted on this site:
http://adamsmith.org/files/capital-gains-tax.pdf
You'll see a graph showing a very marked inverse correlation between the top tax rate on capital gains and taxable realizations.
And if policymakers actually did somehow manage to create a draconian capital gains tax increase in such a way that investors couldn't escape it, they would knock a few percentage points off stock values. People have actually written dissertations on modeling the dynamic effects of such changes. They have been exaggerated by some, but no credible, unbiased observer believes they are zero.
The large bulk of public equity is held by retirement accounts in one form or another. Beating up, even if just a little bit, on the retirement accounts of non-affluent working Americans would not seem to be great public policy.
About the only people benefiting from a large capital gains tax rate increase would be politicians who want to score cheap political points by appealing to a dumbed-down public that doesn't understand the issue.
As for municipal bonds, people often forget that you're not avoiding taxation if you buy them -- you're simply paying the tax (although typically at a lower rate) to an entity such as a state, city, or school district. The extent to which the yield is lower than a taxable instrument with a similar risk profile is the tax.
Stripping the tax-favored status from munis would simply create demands for
even larger bailouts of profligate states. The administration and congress certainly wouldn't want to risk diminishing state and local politicians' abilities to buy the votes of public employee union members and other favored constituencies with other people's money.